A strength test is performed in which a differential pressure and bending that occur in the sky are input into a specimen of the fuselage etc. of an aircraft.
As part of the strength test, an internal pressure test is performed in which the inside of a specimen (barrel) of a cylindrical fuselage panel structure is pressurized.
Since the cylindrical fuselage panel structure is a huge structure, not only is the production cost of the specimen high, but also a large space is required to install a testing device on which the specimen is set. Moreover, due to the time taken to raise the pressure of the cylindrical space inside the specimen to a required pressure, it takes an enormous amount of time to obtain results of a fatigue strength test after repeated pressurization and pressure release into the atmosphere.
Therefore, the test may be performed on a partial specimen that corresponds to a part in need of testing of a fuselage panel structure in the circumferential direction, such as a portion where there is an opening (Patent Literature 1).
FIG. 10 schematically shows an internal pressure testing device 9 that applies an internal pressure to a curved partial specimen 91.
The partial specimen 91 has a skin 92 forming the surface of a fuselage, frames 93 supporting the skin 92, and stringers 94 reinforcing the skin 92. The frames 93 and the stringers 94 are internal structural members provided on the inner side of the skin 92.
The internal pressure testing device 9 includes a pressure vessel 96 between which and the inner side of the partial specimen 91 a cavity 95 is formed, and rods 97 that restrain the partial specimen 91 against an internal pressure applied thereto. As the cavity 95 is injected with air and pressurized, an internal pressure equivalent to the differential pressure between the outside air pressure and the cabin pressure during flight acts on the partial specimen 91. A sealing member 98 that seals the cavity 95 is disposed annularly between the partial specimen 91 and the pressure vessel 96.